Method and apparatus for crimping electrical connectors



July 22, 1969 J. w. BALDYGA METHOD AND APPARATUS FOR CRIMPING ELECTRICALCONNECTORS 3 Sheets-Sheet 1 Filed Nov. 21, 1966 INVLNTOR. JO EPH w.BALDYGA BY 1 M25 '4 4/ "'fia ATToRNEv/s y 1969 J. w. BALDYGA 3,456,480

METHOD AND APPARATUS FOR CRIMPING ELECTRICAL CONNECTORS Filed Nov. 21,1966 s Sheets-Shet :1

FIG.3 FIG-4 INVENTOR. JQSEP W. BALD GA BY a n w 4 MAM L ATTORNEYS July22, 1969 J. w. BALDYGA 3,456,480

METHOD AND APPARATUS FOR CRIMPlNG ELECTRICAL CONNECTORS Filed Nov. 21,1966 v5 Sheets-Sheet 5 INVENTOR.

[17PM W. BALDYGA BY x 61/4 ATTORNEZ United States Patent F U.S. Cl.72--362 2 Claims ABSTRACT OF THE DISCLOSURE The present disclosurerelates to a method and apparatus for crimping electrical connectors inwhich crimping pressure is applied by a plurality of interconnectedtoggle devices, the final toggle preferably being operated slightlyover-center to produce a re-striking operation.

This is a continuation-in-part of application Ser. No. 458,141, filedMay 24, 1965, and now Patent No. 3,374,657, issued Mar. 26, 1968.

At the present time electrical connectors are crimped to the end ofinsulated wire by an operation in which one or more pairs of tabs formedon the electrical connector are crimped over into engagement with theelectrical conductor or the insulation surrounding the electricalconductor, or preferably both. The lectrical connectors are ordinarilyformed of brass and it has been found that best results are obtainedwhen the crimping force is applied in such a way that substantially themaximum crimping force is maintained for a sensible time interval. Inother words, crimping by impact is not satisfactory.

It is an object of the present invention to provide a method andapparatus for crimping electrical connectors to insulated conductorscharacterized in the provision of maintaining crimping pressure for asensible interval as for example about onetenth of a second.

More specifically, it is an object of the present invention to provide amethod and apparatus for crimping electrical connectors to conductorsemploying double toggle mechanism with the result that movement of thecrimping ram or press into final position is relatively slow and resultsin maintaining substantially maximum crimping pressure for a sensibleinterval.

It is a further object of the present invention to provide crimpingmechanism of the character described comprising a rotatable driver,toggle actuating mechanism, selectively operable means for connectingthe toggle actuating mechanism to the driver, and means forautomatically disengaging the toggle actuating mechanism from therotating driver after one actuation of the toggle mechanlsm.

It is a further object of the present invention to provide apparatus ofthe character described comprising a crimping ram, a toggle connected tosaid crimping ram, a second toggle connected to the first mentionedtoggle, and means for actuating the second toggle to produce movement ofthe crimping ram characterized in extremely slow movement of the finalcrimping position, and extremely slow movement out of crimping positionso that in effect, substantially maximum crlmplng pressure 1s maintainedfor a sensible interval.

It is a further object of the present invention to provide crimpingmechanism comprising a rotary member adapted to move throughapproximately 360 degrees to effect a single crimping operation, acrlmplng ram, toggle mechanism connected between said ram and saidrotary member, a cam connected to said rotary member, and work feedmechanism actuated by said cam.

3,456,480 Patented July 22, 1969 It is a further object of the presentinvention to provide apparatus as described in the preceding paragraphin which the cam for actuating the work feed mechanism is provided withan abrupt fall-off positioned to register with a cam follower when thetoggle mechanism is in substantially collapsed position.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, illustrating preferred embodiments of theinvention, wherein:

FIGURE 1 is an elevational view of the crimping apparatus.

FIGURE 2 is a plan view of the apparatus shown in FIGURE 1, partlysectioned on line 22, FIGURE 1.

FIGURE 3 is an elevational view of the apparatus shown in FIGURE 1,viewed from the right.

FIGURE 4 is a sectional view on the line 44, FIG- URE 1.

FIGURE 5 is a sectional view on the line 5-5, FIG- URE 1.

FIGURE 6 is a fragmentary sectional view on the line 6- 6, FIGURE 4.

FIGURE 7 is a fragmentary perspective view showing an electricalconnecter crimped to an insulated electrical conductor.

Referring first to FIGURE 7 there is illustrated a typical applicationof the crimping operation to connect an electrical connector to aninsulated electrical conductor. As seen in this figure, the insulatedelectrical conductor comprises an elongated electrical conductingelement such for example as a copper wire or assembly of copperfilaments indicated at 10. Insulation 12 surrounds the electricalconductor. The electrical connector, which may be of brass or the like,may be in the form of a plate 14 having a pair of ears or tabs 16adapted to be bent around and crimped into clinched engagement with theinsulated conductor, and more specifically, with the insulating cover 12thereof. At the same time, a pair of smaller ears or tabs 18 areprovided which are crimped around and firmly clinched to the bared endof the electrical conductor. The plate 14 may be provided with suitableformations for cooperation with elements of an electrical circuit and inthe present instance this is illustrated simply as comprising a circularopening 20 formed in the end portion of the connector.

Since the electrical connector has two pairs of tabs which arerespectively firmly clinched to the insulating cover of the electricalconductor and to the conducting core or element thereof, the connectoris firmly and permanently attached to the conductor.

It has been found that the clinching of the tabs to the conductor asabove described is best accomplished when crimping pressure is appliedin such a way that substantially maximum pressure is maintained for asensible interval. This is to be contrasted with a clinching operationin which tabs are clinched by extremely brief application of pressuresuch for example as by impact.

The method suggested in the foregoing is adapted to be carried out bythe apparatus illustrated herein.

Referring now to FIGURES 1-6, the apparatus comprises a frame 22 towhich a motor 24 is connected, the motor driving a pinion 26 which is inmesh with a gear 28 mounted for free rotation on a shaft 30. Securelyfixed to the shaft 30 is a collar 32 the connection to the shaft beingillustrated in FIGURE 4 as including a pointed set screw 34, the pointedend of which is received in a recess in the shaft 30. Slidably carriedby the collar 32 in a channel 36 is a pin 38 having a radiallyprojecting dog 40. The pin 38 is provided with an elongated recess 42 inwhich is received a compression spring 44 the outer end of which seatsagainst a disc 46. With this arrangement the spring 44 biases the pin 38to the right as seen in FIGURE 4. Movement of the pin 38 to the right isnormally prevented by engagement between the dog 40 on the pin 38 with adepending flange 48 formed on a lever 50 which is pivoted as indicatedat 52 and is adapted to be moved upwardly by momentary energization ofthe windings of a solenoid 54. The gear 28 is provided with a plurality,as for example six, openings in circumferential alignment with the pin38 and when the pin is freed for movement under the action of the spring44 the pin moves into the next opening in the gear, and thus, directlymechanically couples the gear 28 to the collar 32. As a single rotationof the collar 32 nears completion, the dog 40 on the pin 38 engages acamming surface on the flange 48 so that the pin is retracted from theopening in the gear 28. The lever 50 carries a dog 56 which is engagedby the dog 40 on the pin, thus arresting rotation of the collar 32 after360 degrees of rotation.

The collar 32 of course, during its rotation imparts rotation to theshaft and this shaft in turn rotates a combined cam and crank arm 58having a crank pin 60 thereon.

Mounted on the exterior of the frame 22 is a pivot mounting pin 62, thepin being rigidly mounted in a boss 64 as best seen in FIGURE 2.Connected to the pin 62 are a pair of links 66 which are connected by apivot pin 68 to a pair of links 70 and a second pair of links 72. Thelinks 72 have the opposite end connected to crank pin 60. Links 70 areconnected to a pin 74 and to this pin are also connected the links 76and 78. The opposite end of the links 76 are connected to a pin 80 whichin turn is supported in openings in a plurality of leaves 82 formed on asupport member 84 having the circular flange 86 engaged against athreaded abutment member 88. Support 84 is retained in assembledrelation against the adjustable member 88 by a screw 90 carried by a cap92.

The other ends of the links 78 are connected to a pin 94, the pin beingcarried by a driver 96, the driver having a circular base portion 98 andvertically extending leaves 100, and a central relatively thick leaf102. The circular base of the driver 98 is received in a similarlyshaped recess 104 in the ram 106 which is vertically slidable in a guidehousing 108, as best seen in FIGURE 2. In this figure it will beobserved that the ram 106 has four corner portions 110 each of which isguidingly re ceived in a correspondingly shaped corner 112 of the guideand housing member 108. Thus, the ram 106 is firmly supported forrectilinear movement upon actuation of the toggle mechanism. It willfurther be apparent that the downward limiting position of the ram 106may be accurately predetermined by adjustment of the adjustable abutmentmember 88.

Referring now to FIGURE 1 it will be observed that the links 66 and 70form a first toggle in which the toggle elements are moved intosubstantial alignment when the actuating links 72 are in the positionshown in this figure. The first toggle mechanism comprising the links 66and 70 is connected to the second toggle mechanism comprising the links76 and 78 and the relationship is such that when the links of the firsttoggle mechanism approach substantial alignment the links 76 and 78 ofthe second toggle mechanism also approach alignment. Thus, it isapparent that as the ram 106 approaches its lowermost position, it ismoving extremely slowly and also it is capable of applying forces ofrelatively great magnitude with only moderate power being supplied tothe drive pinion 26.

More important than the relatively great magnitude of the pressurecapable of being applied by the ram is the fact that the describedarrangement in effect operates to maintain the pressure applied to aworkpiece such as an electrical connector, at approximately the samepeak value for a sensible interval. In practice, the apparatus issemiautomatic in that the uncrimped connectors are automatically fed tocrimping position while the ram is at the top of its stroke and theoperator inserts the prepared conductor end so that the bared conductoris positioned between one pair of tabs, and the insulating coveradjacent the bared ends is positioned between the other pair of tabs onthe connector. At this time the operator energizes the solenoid 54momentarily. In practice, 'the solenoid may be energized by dischargefrom a condenser. Energization of the solenoid raises the lever 50 andreleases the pin 38 for movement into coupling engagement with the gear28. The collar 32 is given 360 degrees of rotation and as it completessuch rotation the pin is retracted so as to disconnect the collar fromthe gear and rotation of the collar and associated mechanism is rterminated in precise position by engagement between dogs 40 and 56.

Referring to FIGURE 1, there is illustrated a cam surface engageable bya roller 122 on a lever 124 pivoted to the frame 22 as indicated at 126.The lever 124 is biased to the left as seen in this figure by a tensionspring 128 and is adapted to connect with mechanism (not shown) foreffecting feed of an uncrimped connector into position beneath the ram106. Details of the crimping head and the base which receives theuncrimped connector are omitted since these elements are of coursedesigned in accordance with each particular crimping operation to beperformed. It will be observed however, that the cam surface 120includes the abrupt fall-off portion 130 which is adapted to move intoposition adjacent the roller 122 when the two toggles are substantiallycompletely collapsed. Thus, feed of the connector is accomplished veryquickly when the ram is in its uppermost position, thus affordingmaximum clearance and at the same time, the arrangement provides for aminimum of delay in conditioning the apparatus for the succeedingcrimping operation.

While the force supplied in the crimping operation is of course variablein accordane with the particular connector, it has been observed that apressure of 23,400 pounds has been developed when the press is .001displaced from its maximum downward movement, using a /2 horsepowermotor operating at 1750 rpm. The gear ratio between the pinion 26 andthe gear 28 is such that shaft rotation is at the rate of rpm. This ofcourse means that only .333 second is required for complete rotation ofthe shaft or for a complete downward and upward reciprocation of theram. However, with the arrangement of the crank and double toggle, abouthalf of this time or aproximately one-sixth of a second, is taken up bythe last .015" of movement of the ram. Thus, the cycle involves acrimping operation in which the pressure is increased at a controlledbut increasing rate and is maintained at relatively high values for asensible interval. While variations are possible and are in accordancewith the material and shape of the connectors, it may be stated that theapplication of pressure adequate to crimp the connector tabs intorequired position should be maintained for an interval of at least .100second.

In the foregoing the toggle links 76 and 78 are disclosed as inalignment, the axes of the pivot connections 74, 80 and 94 occupying avertical plane. However, it is preferred to dimension and adjust theparts so that in the operating stroke of the press, the pivot pin 74moves slightly beyond the vertical plane containing the axes of the pins80 and 94, or in other words, moves to a slightly over-center positionwith respect to the toggle.

As a result of this the final down stroke of the press involves a veryslight upward movement of the ram followed by a correspondingly slightdownward movement before it moves upwardly into retracted position. Thisresults in an operation which is known in the industry as restriking andmaterially improves the operation in that the crimped piece due to there-striking operation, tends to retain its fully crimped conditionwithout any relaxation.

It will of course be appreciated that in addition to restrikingresulting from the slightly over-center movement of the pivot pin 74,the operation results in effectively holding the crimped element incrimped position for a substantially longer period than is the casewhere the pivot pin 74 merely reaches the center position and is thenretracted.

Excellent results are obtained when the parts are dimensioned andadjusted so that the axis of the pivot pin 74 moves approximately .040"beyond center. It is preferred to limt the over-center movement of thepivot pin 74 to between .010" and .080".

The drawings and the foregoing specification constitute a description ofthe improved method and apparatus for crimping electrical connectors insuch full, clear, concise and exact terms as to enable any personskilled in the art to practice the invention, the scope of which isindicated by the appended claims.

What I claim as my invention is:

1. The method of crimping electrical connectors to electrical conductorsin which tabs on the connectors are bent around and crimped against theconductors, comprising the step of applying crimping pressure to thetabs, and maintaining the crimping pressure for a sensible interval ofat least 0.100 second.

2. The method of crimping electrical connectors to electrical conductorsin which tabs on the connectors are bent around and crimped against theconductors, comprising the step of applying crimping pressure to thetabs rapidly until crimping pressure is approached, thereaftercontinuously decreasing the rate of increase in pressure until maximumpressure is reached, thereafter slightly decreasing pressure, thereafterslightly increasing pressure to re-strike the connector, and finallyreducing pressure at an increasing rate, whereby pressure is maintainedfor a sensible interval with only slight change in magnitude.

References Cited UNITED STATES PATENTS 337,297 3/1886 Berry 72--4513,064,706 11/1962 Ehmann 72451 RONALD D. CREPE, Primary Examiner U.S.Cl. X.R. 72-372, 416, 451

